BIOL 204 Lab For Week 12

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BIOL 204 Lab For Week 12 Digestive
Enzymes
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• Digestive Enzymes
• are used in the lumen of the GI tract to break
  down complex molecules into absorbable subunits
• Enzymes are biological catalysts which increase
  the rate of a chemical reaction without
  themselves becoming part of the product

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In this experiment we will observe the activity
of three different enzymes
Amylase digests starch into disaccharides
Trypsin digests proteins into peptides
Lipase digests fats into glycerol and fatty
acids
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• Variables tested
• Incubation temperature
• How will enzyme activity compare when incubated
  at O o C and 37 o C?
• Denaturization of Enzymes
• How will enzyme activity be altered if the enzyme
  is denatured by boiling?

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Activity 1 Trypsin Activity Trypsin an
enzyme, secreted by pancreatic acinar cells, that
hydrolyzes proteins into small fragments
(peptones, peptides and proteoses)
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In this experiment, trypsin will act on an
artificial substrate to yield a yellow colored
product Trypsin BAPNA
H2O N-benzoyl-L-arginine p-nitroaniline
(yellow) 1. Reaction rate will be compared at
these different incubation temperatures 370
C and 0o C What do you predict will happen?
2. The rate of the reaction will be determined
using boiled trypsin. What do you predict will
happen?
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Activity 2 Amylase Activity Amylase is a
carbohydrate digesting enzyme, produced by
salivary glands and pancreatic acinar cells,
that hydrolyzes starch into maltose
(disaccharides) Amylase Starch H2O maltose
(disaccharides)
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Indicators Starch IKI (Lugols solution) -
turns blue/black in the presence of
starch Benedicts Solution turns
green/orange/ red/brown in the presence of
reducing sugar
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IKI Test For Starch in a Spot Plate Benedicts
Test for reducing sugar in heat test tubes
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As in activity one, the reaction will be observed
under different conditions Boiled Enzyme
(Amylase) Incubation Temperature 0oC and
37oC
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Activity 3 Lipase Activity Lipase is a
hydrolytic enzyme, made primarily by pancreatic
acinar cells, that hydrolyzes neutral fats into
fatty acids and glycerol Lipase Fat
H2O Glycerol Fatty Acids
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Fat Digestion
Indicator Blue litmus terns pink (red) in
the presence of acid (one the products is
fatty acids)
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Bile emulsifies fat.
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In this activity, you will examine the effect
of incubation temperature (0oC vs. 37oC)
and addition of bile salts on the reaction